The present invention relates to an image forming unit and an image forming apparatus.
Generally, an image forming apparatus such as a printer, a copier, a facsimile machine, a complex machine or the like includes process cartridges (i.e., image forming units) of black, yellow, magenta and cyan. Further, LED heads, transfer rollers and the like are provided so as to face the respective process cartridges. Each process cartridge includes a photosensitive drum, a charging roller, a developing unit, a cleaning blade and the like. The developing unit includes a developing roller, a toner supplying roller, a developing blade and the like. Components of the process cartridge are housed in a cartridge main body, and a toner cartridge is detachably mounted onto the cartridge main body.
The charging roller uniformly charges the surface of the photosensitive drum, and then the LED unit irradiates the surface of the photosensitive drum to form a latent image. The developing roller holds a toner (i.e., a developer) thereon, and causes the toner to adhere to the latent image on the surface of the photosensitive drum, so as to form a toner image. The transfer roller transfers the toner image from the photosensitive drum to a sheet. By transferring the toner images of the respective photosensitive drums of the image forming units to the sheet, a color toner image is transferred to the sheet. Then, a fixing unit fixes the color toner image to the sheet, so that a color image is formed on the sheet.
The toner remaining on the photosensitive drum after the transferring of the toner image is removed therefrom by the cleaning blade, and such a waste toner is collected in a waste toner chamber provided in the toner cartridge.
A configuration for conveying the waste toner to the waste toner chamber of the toner cartridge is as follows. A groove is formed on a side frame of each process cartridge. The groove extends in the form of a loop along the side frame. Further, a toner conveying belt is provided in the groove. The toner conveying belt has a plurality of teeth on an outer circumferential surface. The toner conveying belt moves to convey the waste toner (collected from the cleaning blade) to the waste toner chamber (see, Japanese Laid-open Patent Publication No. H11-73078).
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